This is just as the Messenger of Allah used to perform raids in
the early morning. He
would wait to see if he heard the Adhan (call to prayer)
from the people. If he heard it he would leave them alone, and
if he didn't hear it he
would attack.

It is also possible that the pronoun (He) could be referring to
man. This was said by Muhammad bin Ka`b Al-Qurazi. Thus, its
meaning would be that man is a witness himself to the fact that
he is ungrateful.

This is obvious in his condition, meaning this is apparent from
his statements and deeds.